Primary pulmonary hypertension (PPH) is a progressive disease characterized by obstruction of small pulmonary arteries. The currently funded project "Pulmonary Hypertension: Mechanisms and family Registry" discovered linkage of familial PPH four years ago and recently identified that mutations in bone morphogenetic protein receptor II (BMPR2) cause PPH. Our group at Indiana University has extensive experience in the analysis of large data sets utilized to detect susceptibility genes for complex disease. During the next five years, the specific aims of Core B: Genetic Analysis and Bioinformatics will be: 1. To modify and adapt the study designs of the projects methodological advances in genetic analyses; 2. To perform linkage analyses to determine if there are modifying the age at onset of PPH. 3. To perform QTL analyses to map modifiers of murine 4. To perform association analyses to evaluate the role onset of PPH.